The Cooperative Breast Cancer Tissue Resource (CBCTR) is sponsored by the National Cancer Institute to provide archival, paraffin-fixed specimens for the study of molecular markers. Kaiser Permanente, Portland, Oregon (KPNW) has been an active member of this project since 1994 and seeks to continue in this role in the next funding period. The CBCTR has collected over 9000 specimens of breast cancer tissue and linked it to demographic, clinical and outcome variables from cancer registries and medical records. The pathological material can be supplied as sections of blocks from the initial surgery undergone by individual patients or as a Tissue Microarray that combines tissue cores from hundreds of specimens. Researchers may apply for this material to enable the testing and/or validation of candidate prognostic markers. An independent Research Evaluation Panel evaluates these requests for scientific merit and technical feasibility. The Coordinating Committee of the CBCTR, comprising the Principal Investigators of the four sites, reviews these requests for appropriateness for the Resource. Considerations include the likelihood of success, impact on workloads and effect on the continuing operation and usability of the Resource. KPNW has contributed over 2400 specimens and distributed hundreds of tissue samples in the process of filling requests from researchers in the community. In addition, KPNW investigators and staff have contributed to the development and modifications of the procedures used in daily operations, to papers and presentations about the CBCTR, to displays at scientific meetings and to publicity efforts in the scientific community. As the CBCTR approaches its goal of wider use of its specimens, particularly of the TMAs, KPNW stands ready to replenish the collection with more, previously unexamined specimens from our files.